Form for paving blocks



Oct. 20, 1942. w, FQ SB RG j 2,299,318

FORM FOR .PAVING BLOCKS v Filed Jan. 6, 1940 I IN VEN TOR;

ATTORNEY Patented Oct. 20, 1942 UNITED STATES PATENT OFFICE FORM FOR,PAVING BLOCKS George W. Forsberg, Albany, Calif.

Application January 6, 1940, Serial No. 312,695

3 Claims.

The present invention relates to forms for paving blocks, andparticularly to forms adapted for use in casting blocks in placedirectly upon the surface to be paved.

It is the object of the invention to provide forms that may be used inthe building of pavement to create a paved surface of separate butinterlocked blocks of relatively small dimensions in order to overcomethe ill effects of warping, expansion, and cracking which occur in largeslabs, and to provide forms which remain in place after the pavingmaterial is poured between them to function as expansion joints for theblocks.

A further object is to provide forms for casting paving blocks in placewhich will serve as ideal receptacles for concrete or the like to bepoured into them, and which will serve to induce proper curing of theconcrete and to provide a suitable expansible material between adjacentblocks after they are cured.

Further objects and advantages of the invention will be made apparent inthe following specification, wherein the invention is described indetail with reference to the accompanying drawmg.

The drawing and description relate to forms particularly adapted forlaying pavement on a street or highway, and the material of which thepavement is formed will be referred to as concrete. It will beunderstood, however, as the description proceeds, that the forms areadapted to other uses, such, for example, as laying floors in largebuildings, lining water canals, and many other uses where it isotherwise common practice to cover a surface with a paving material.

Furthermore, the word concrete as used herein is intended to refer toany cement-like or plastic material capable of being poured in forms toprovide a pavement or similar surface.

In the drawing- 7 Fig. 1 is a perspective view of a small portion of asurface to be paved, showing the forms of the present invention in placeto receive the paving material;

Fig. 2 is a vertical sectional view taken on the line II-II of Fig. 1;

Fig. 3 is an enlarged section taken on the line IIIIII of Fig. 1 andillustrating a modification of the form shown in Fig. 1;

Fig. 4 is an enlarged vertical transverse section of the upper edge ofany one of the form members illustrated in Fig. 1, showing details ofconstruction thereof;

Fig. 5 is a similar section of the lower edge of the same number; and

Fig. 6 is a horizontal section taken on line VIVI of Fig. 1.

Referring first to Fig. I, the forms of the invention are shown ascomprising a plurality of parallel spaced elongated form members II]with short form members I I extending between adjacent members III atspaced intervals in a manner to divide the elongated spaces between themembers I0 into courses of staggered reticules for the reception ofconcrete which, when poured in these spaces and leveled off to the topsof the forms, will provide individual paving blocks separated from eachother only by the material of which the forms are made.

The form members I!) and II are disposed at an angle to the vertical, asshown in Figs. 1 and 2, and angularity of the members [0 is alternatelyreversed. The angularity of the members II is likewise alternatelyreversed, the result being that all of the blocks cast in the form willhave inclined side walls, each wall being parallel to the adjacent wallsof abutting blocks. The inclination of the forms is such that the blockswhen cast and cured will have a tendency to lie together as though theywere formed of a single slab, although they are sufficiently separatedto prevent cracking or warping as a result of stresses which may be setup, for example, as by expansion and contraction or slight settling ofthe base upon which they are cast. This slight inclination of the sidewalls is such that the overhang of the upper edge of the blocks withinwardly sloping side walls will not be sufiicient to induce breakingoff of the upper edges of the blocks when they are subjected to a load,and any tendency toward cracking of the blocks at their edges due tothis incline is also overcome by the construction of the upper edges ofthe form members, presently to be described in detail.

The construction of the form members is shown in cross section in Figs.4 and 5, wherein each member is shown as comprising outer layers offlexible moisture resistant material I2, and an inner layer I3 ofcompressible material adapted to compensate the Variation of the spacebetween the blocks upon expansion and contraction which may result fromtemperature variations. The material forming the layers [2 is preferablypasteboard impregnated with a water resistant material such asparaffine, varnish, or any suitable composition that will retain orsupplement the rigidity of the pasteboard and prevent its absorbing anymaterial amount of moisture from the concrete which is poured againstit. The layer I3 of material which is placed between the layers I2 maybe a thick paper-like material of bituminous base or other semi-plasticsubstance, preferably bituminous, suitable for the formation of anexpansion joint. As the blocks of which the pavement is formed are ofrelatively small dimensions, the expansion possibilities for any singleblock are very small and the combined thickness of the layers I2 and I3may .be as thin as it is practical to make them and still retainsufiicient rigidity for the casting of the concrete.

Each of the form members is provided with a base member as shown in Fig.5, which member is formed by bending the layers I2 outwardly to a planeparallel to the ground and then reinforcing them with a strip I4 ofsimilar material which is preferably curved upwardly and inwardly andpressed or crimped into position with its :edges I5 overlying theoutwardly extending portions of the members I2. .This-base.-serves:as asupport for the members and H in their slightly inclined position, andthe =members l'l are preferably of slightly less height than the membersI'Il'so that their base members willoverlie :the basemembers of themembers -I lastshown in Figs. 1 and 2. The base members of the members1:0 and 1 I combine to provide inwardly projecting flanges in each ofthe spaces in 'which concrete is to be poured, soithat if desired abottomimay be provided for the forms, which .bottom may bea rectangularsheet of paper impregnated' with a material to resist moisture .and of asize to fit within the .castin'gspace with its edges overlying the baseflanges of the .form members. The useaof such a bottomamember willprevent .undesiredabsorption .of .moisture or cementpaste from the.concrete by the .underlying grade surface before the concrete hasbeenproperly cured. V

.The upper edges of the form members Haredesigned -.as illustrated inFig. .4 to .form :rounded edges on the blocks to .prevent crushing orcrackinglof their edges .due'to the load thatwill be imposed uponthem'by wtraiific, and also incorporate means to prevent the.expansible' material I3 from exuding upwardly 'onto the surface of thepavement, as frequently occursin other pavements in warm weather, andwith means to serveas aguide in surfacing the blocks after they arepoured. .As shown in Fig. 4,:the "two layers of paper-like material I.2are "flared outwardly as at I6 .to .serve as forms for rounded cornerson adjacent blocks. Afilleriof rubber orother similar resilientmaterialmay .be inserted between the outwardly flared portions I6 and"may consist of 'aflat strip bentupon itself to form a tubelike memberI! with a projecting flange 'I'8 of double thickness which may besecured between the members I2 by rivets .or clips I9. A'molded rubberstrip may be used for this purpose "if desired. The rivets or clips I9also serve to retain the upper edges of the form members I2" and I3against separation, and while thesemembers may be pressed or rolledtogether and will normally adhere to each other sufficientlyto prevent.separation "throughout the greater part :of their :surfaces, rivets orother fastening meanssuchasindica-ted at I9 may be used at intervalsfurtherto insure against .their'separatiomif :desired.

.Apasteboard strip 2!] preferably .caps the form member and has itsedges bent downwardly'and inwardly-as indicated at 2I to. retain .it :inplace and to brace and protect the outwardly flaredportion I6 of themembers I2. When the forms are assembled in the manner illustrated inFig. 1, metal screeds shown at 22 in Fig. 4 may be used to protect theupper edges and serve as guides for leveling off the tops of the blocksand insure a uniform pavement surface. The screeds 22 may be placed atnecessary intervals, and being of channel-shaped cross section, will beeasy to place and remove. After the blocks have been cast, the screeds22 may be pulled off and will leave, adjacent the edges of the blocks, aslight downward step and then a gradual curve which will lend anappearance that is neat and provide a surface that has enough roughnessto prevent skidding without producing bumps noticeable to the ordinaryrubber tired vehicle.

The upper outwardly flared portion I6 of the members I2 may remain inplace or may be worn away by weather and traffic, but the rubber memberI1 will remain in place and prevent the plastic material I3 from beingexuded, onto the surface of the pavement.

In order that the blockswvill be securely interlocked with relation toeach other and in a manner to prevent longitudinal sliding or twistingmovement between adjacent courses, the forms are provided with recesses25 in their walls, adapted to produce complementary tongues and groovesin the abutting side walls of adjacent blocks. The recesses 25, whichare preferably largest in cross section at their lower ends and taperedupwardly to a point short of the .top edges of the blocks, arepreferably formed asillustrated in Fig. 6 by cutting away a portion-ofthe form wall and projecting a channel-shaped form member 26therethrough. Themember 26 is provided with flanges 2'! along itssideand top edges, which flanges are secured to the form wall by meansof rivets 28 or any other suitable means for securing them in place. Themembers 25 are preferably formed of the same material as the form walls,so that the small space between the registering tongues and groovesformed in the blocks will be filled with expansible material.

'The short form members II are retained .in place between the longerform members! by means of elongated clips 30 of metal, impregnatedpasteboard, or other suitable material (see Figs. 1 and 3), which clipsare secured to the form members II] by means of prongs 3I piercing themembers and bent over at their ends. The clips 30 are formed of stripswith their outer edges bent inwardly to form resilient retaining flanges32 adapted to engage opposite sides of the form members II. The formmembers II have flanges 33 pressed outwardly from their edges to engageunder the clips 32 and positively prevent their removal from the clips.

The members 25 and clip members 30 will lend rigidity to the forms sothat they may be made of very thin material and yet stand up during thepouring of concrete or other material of which the paving blocks are tobe made. If it is desired further to supplement the rigidity of the.forms, stiifeners 35, as shown in Figs. 1 and 6,

may be used. These stiifeners may be formed of light metal strips with acentral longitudinal crease 36 to prevent them from bending and withprongs 31 adapted to pierce the walls of the forms and to be bent overto retain the strips in place. Other means for stiffening the forms maybe used, and one such means is shown in Fig. .3, wherein the material ofthe forms is corrugated as at 40, the corrugations running in a verticaldirection on the form members I0 and I I. These,

corrugations could be used throughout the entire length of the formmembers, but it is preferable that they be provided in spaced groups sothat the major portion of the side wall surfaces of the blocks will beformed on flat planes. The vertical corrugations also serve to make theforms sufficiently flexible to conform to slight curves such as may beencountered in a highway profile.

In use of the forms for paving a highway or the like, a suitablesubgrade is prepared in the usual manner. A blanket of sand or any othercushioning material should preferably be laid over the subgrade andfinished to the desired profile. The forms are then laid upon theprofile and asesmbled in the manner illustrated in Fig. l, the longerforms l being placed preferably transversely to the longitudinal centerline of the highway, and the shorter forms ll being secured in place bymeans of the clips 30, as described above. The forms may then beanchored to the subgrade by spikes or similar means driven through thebottom flanges of the forms. If it is desired to reinforce the blocks,any suitable reinforcing means may be placed within the individual blockforms. Reinforcing members bent to required shape from steel wire will,for example, serve this purpose, and if the wire shapes are made of asize to contact the side walls of the form, they will serve asadditional support for the forms as the concrete is being poured andwill also strengthen the blocks after the pouring. It is to beundertsood, however, that reinforcement of the blocks is not consideredessential but is optional, and that any preferred shape of reinforcingmembers may be used.

The forms having been set up and secured in place as described, they maybe filled with concrete, which is poured approximately to the level oftheir uppermost edges and thereafter trowelled smooth to the level ofthe tops of the screeds 22. The screeds are removed and, after theconcrete has cured and attained sufficient strength, a weighted rollermay be run over the top of the highway to provide a firm contact betweenthe blocks and the surfacing material on the subgrade.

Due to the very small expansion joints between the blocks, thepossibility of moisture leaking through them is reduced to a minimum.They are free to expand and contract the maximum amount possible withoutdanger of cracking, and a durable highway is provided at a low cost, asthe blocks may be made considerably thinner than large concrete slabsand may be placed with considerably less cost than bricks or other smallblocks which are pre-cast and then have to be transported to the site ofthe highway and handled a great deal before they are finally laid inplace.

Blocks may be differently colored for ornamental purposes or to providemarkers for the direction of traffic, and any repairs to the highway orto underlying pipes or conduits may be readily effected, as the blocksmay be removed one at a time and are capable of being replaced in theiroriginal positions, it being necessary usually to cast but one or twonew blocks where a section of pavement has been removed.

Although the blocks have been illustrated and described as of agenerally rectangular shape, it should be understood that the form wallsof which they are made are adaptable to arrangements for the provisionof various shapes and designs. Furthermore, it is not essential that theform walls be arranged at an angle to the vertical, as shown in theaccompanying drawings, as, while this angularity has certain advantagesin highway construction, vertical walls may be used to advantage in somecases.

The particular manner in which the form walls are constructed may bevaried in several ways. For example, the upper portion of the wall, asillustrated in Fig. 4, may be formed without the added cap 20 with theflanges 2| thereon by producing the outer members [2 is a single pieceand bending or rolling them to the general shape shown, incorporatingthe rubber strip 11 in the rolling operation and, if desired,incorporationg reinforcing members in this, as well as other parts ofthe form, wherever they may be required. It is to be understood that theforegoing description and accompanying drawings are for illustrativepurposes and are not intended to limit the invention which may be variedas to the materials employed and the particular construction andarrangement of the several parts shown Within the scope of the appendedclaims.

Having thus described my invention, what I claim and desire to secure byLetters Patent is:

1. In forms for paving blocks or the like, a form wall comprising spacedsheets of paperlike material and an intermediate layer of ex pansiblematerial, said sheets being flared outwardly adjacent the upper edge ofthe wall to provide rounded edges on blocks cast on opposite sides ofthe wall, and a filler member of resilient material incorporated in theform between the outwardly flared upper edges to prevent said expansiblematerial from exuding from the joint between adjacent blocks.

2. A form wall for paving blocks, comprising spaced sheets of paper andan intermediate layer of expansible material, said sheets being flangedoppositely outwardly at the bottom of the wall to provide a base forsupporting the wall in an upright position, and a strip of paperunderlying the outwardly flanged portions and bent upwardly over theiredges to provide a seal for preventing escape of the expansiblematerial.

3. A form wall of the character described, comprising parallel spacedsheets of water-resistant material bent outwardly adjacent their top andbottom edges to provide longitudinal rigidity, a layer of compressiblematerial between said sheets, and a resilient sealing member disposedbetween the upper outwardly bent edges of the sheets to prevent thecompressible material from exuding.

GEORGE W. FORSBERG.

